/*
 * Copyright (c) 2019 Minjie.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 *
 */

#pragma once

#include <queue>
#include <mutex>
#include <assert.h>


/** 
 * A wrapper around the std::queue to make it thread-safe
 */
template <typename T>
class tqueue
{
public:
    tqueue() = default;
    ~tqueue() = default;

    T front(){ 
        std::lock_guard<std::mutex> lock(m_mtx);
        return m_queue.front();
    }

    bool empty(){
        std::lock_guard<std::mutex> lock(m_mtx);
        return m_queue.empty();
    }

    void push(T data){
        std::lock_guard<std::mutex> lock(m_mtx);
        m_queue.push(data);
    }

    void pop(){
        std::lock_guard<std::mutex> lock(m_mtx);
        assert(!m_queue.empty() && "tqueue pop(), but queue empty !");
        m_queue.pop();
    }

    void clear(){
        std::lock_guard<std::mutex> lock(m_mtx);
        while (!m_queue.empty()){
            m_queue.pop();
        }
    }

    size_t size(){
        std::lock_guard<std::mutex> lock(m_mtx);
        return m_queue.size();
    }

private:
    std::mutex m_mtx;
    std::queue<T> m_queue;
};